Search

In this study, the oxygen reduction activity of PrBaCo2O5+δ (PBC) double perovskite is remarkably enhanced by rationally tuning the calcination temperatures of the cathode precursor for solid oxide fuel cells (SOFCs). Effects of the calcination temperatures on the phase structure, microstructure, surface area and oxygen reduction reaction (ORR) activity of PBC cathode is systematically investigated. The cathode with optimized calcination temperature (900 °C, PBC-900) shows excellent activity and stability for ORR at 600 °C in terms of area specific resistances (ASRs). A distinctive low ASR of 0.068 Ω cm2 is obtained at 600 °C for PBC-900, which is 92.6%, 34.6% and 15.0% lower than PBC-800, PBC-1000 and PBC-1100, respectively. After operating for 250 h in air at 600 °C, the ASR value of PBC-900 is not significantly reduced. Furthermore, a single cell with PBC-900 cathode delivers attractive peak power density of 1.60 W cm−2 at 600 °C. The present study suggests that the ORR activity of PBC cathode can be greatly boosted by rationally tailoring the calcination temperatures, which may bring new avenue for the design of highly active cathodes for SOFCs.

Lithium-sulfur batteries have attracted a lot of attention in the recent years. However, the electrochemical performance of lithium-sulfur batteries is greatly affected owing to several issues. In this paper, we designed a polyaniline@spherical ordered mesoporous carbon/sulfur nanocomposite (PANI@S-OMC/S), and S-OMC/S was wrapped by PANI via in-situ polymerization. The inherently conducting nature of PANI increased conductivity of PANI@S-OMC/S electrode to improve the free transfer of electrons, and PANI shell also provided a barrier between the lithium polysulfides and electrolyte to further prevent the occurrence of the “shuttle effect”. Moreover, mesoporous pores are wonderful hosts to contain sulfur to trap the long-chain lithium polysulfides and prevent them from dissolving in electrolyte. A high initial discharge capacity of 1626 mAh/g was achieved for the PANI@S-OMC/S electrode in first cycle at 0.1 C, and the composite maintains 1338 mAh/g after 100 cycles while the coulombic efficiency still remains ∼98%.

A cobalt-free layered oxide-Sr4Fe6O13-delta is synthesized and characterized for application as a cathode of intermediate temperature solid oxide fuel cells. High temperature powder xray diffraction, oxygen temperature programmed desorption and electrochemical impedance spectroscopy are employed to evaluate the temperature-dependent crystal structure and oxygen reduction reaction (ORR) activity of Sr4Fe6O13-delta. The oxide exhibits a single phase between room temperature and 1050 degrees C with low thermal expansion coefficient. The drawback of this oxide lies on its low ORR activity which is likely due to its layered structure which favors oxygen ionic transport two-dimensionally in the ac plane along the layered oxide layer. We show here that the original ORR activity can be improved by adjusting the phase compositions through an oxygen-deficient calcination process. An area specific resistance of 0.139 Omega cm(2) at 700 degrees C is attained by calcining Sr4Fe6O13-delta at 900 degrees C with similar to 66.2 wt% of perovskite phase in the composite material. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Various Ni–LaxCe1−xOy composites were synthesized and their catalytic activity, catalytic stability and carbon deposition properties for steam reforming of methane were investigated. Among the catalysts, Ni–La0.1Ce0.9Oy showed the highest catalytic performance and also the best coking resistance. The Ni–LaxCe1−xOy catalysts with a higher Ni content were further sintered at 1400 °C and investigated as anodes of solid oxide fuel cells for operating on methane fuel. The Ni–La0.1Ce0.9Oy anode presented the best catalytic activity and coking resistance in the various Ni–LaxCe1−xOy catalysts with different ceria contents. In addition, the Ni–La0.1Ce0.9Oy also showed improved coking resistance over a Ni–SDC cermet anode due to its improved surface acidity. A fuel cell with a Ni–La0.1Ce0.9Oy anode and a catalyst yielded a peak power density of 850 mW cm−2 at 650 °C while operating on a CH4–H2O gas mixture, which was only slightly lower than that obtained while operating on hydrogen fuel. No obvious carbon deposition or nickel aggregation was observed on the Ni–La0.1Ce0.9Oy anode after the operation on methane. Such remarkable performances suggest that nickel and La-doped CeO2 composites are attractive anodes for direct hydrocarbon SOFCs and might also be used as catalysts for the steam reforming of hydrocarbons.

Nowadays, there is a doubt about the electrochemical contribution of silver current collector on the oxygen reduction reaction (ORR) over oxide electrodes in SOFCs since many reports have demonstrated that the modification of porous oxide electrodes with nano-size silver can obviously improve the electrocatalytic activity for ORR. In this study, the electrochemical contribution of silver current collector to the performance of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ (BSCF) electrode on Sm 0.2 Ce 0.8 O 1.9 (SDC) electrolyte for ORR was specifically investigated. The active layer of BSCF electrode was found to be around 25 μm by using both silver and gold current collectors. Much better performance was demonstrated by using silver current collector, both from symmetric cell and single cell tests. However, EIS of silver on SDC electrolyte demonstrated the silver alone as electrode actually had poor performance for ORR. In addition, SEM-EDX confirmed that there was no silver diffused from the current collector layer to modify the porous BSCF electrode. Interestingly, the activation energy for oxygen reduction over BSCF electrode was reduced by applying silver current collector. We then proposed a mechanism to explain the improved electrochemical performance of BSCF electrode by considering the high activity of silver for oxygen surface diffusion.

Compared with planar SOFCs, tubular SOFCs have the advantages of facile sealing and easy scale up. In this study, a tubular anode-supported thin-film YSZ electrolyte SOFC was successfully fabricated by extrusion of the anode substrate in combination with wet powder spraying of the electrolyte layer. The fuel cell performance was tested by applying either hydrogen or methane as the fuel and ambient air as the cathode atmosphere. Peak power densities of 432 and 145 mW cm −2 were achieved respectively at 800 and 600 °C for a cell with conventional LSM and silver wire as the cathode and the current collector. The performance was further improved by adopting BSCF cathode with an SDC buffer layer. EIS demonstrated the large electrode polarization resistance is the main source of cell resistance, while the contact resistance is also not negligible. The performance of the cell directly operating on methane fuel was also investigated. A special operation mode by alternatively operating on methane and hydrogen fuels was adopted, which can effectively increase the cell operational stability.

On the purpose to perform as functional layer of SOFCs operating on methane fuel, NiFe–ZrO 2 alloy catalysts have been synthesized and investigated for methane partial oxidation reactions. Ni 4 Fe 1 –ZrO 2 shows catalytic activity comparable to that of Ni–ZrO 2 and superior to other Fe-containing catalysts. In addition, O 2 -TPO analysis indicates iron is also prone to coke formation; as a result, most of NiFe–ZrO 2 catalysts do not show improved coking resistance than Ni–ZrO 2 . Anyway, Ni 4 Fe 1 –ZrO 2 (Ni:Fe = 4:1 by weight) prepared by glycine-nitrate process shows somewhat less carbon deposition than the others. However, Raman spectroscopy demonstrates that the addition of Fe does reduce the graphitization degree of the deposited carbon, suggesting the easier elimination of carbon once it is deposited over the catalyst. Ni 4 Fe 1 –ZrO 2 has an excellent long-term stability for partial oxidation of methane reaction at 850 °C. A solid oxide fuel cell with conventional nickel cermet anode and Ni 4 Fe 1 –ZrO 2 functional layer is operated on CH 4 –O 2 gas mixture to yield a peak power density of 1038 mW cm −2 at 850 °C, which is comparable to that of hydrogen fuel. In summary, the Ni 4 Fe 1 –ZrO 2 catalyst is potential catalyst as functional layer for solid-oxide fuel cells operating on methane fuel.

In order to increase the coking resistance of SOFCs operating on DME fuel, a Pt/Al 2 O 3 –Ni/MgO mixture catalyst was investigated for internal partial oxidation of DME. Catalytic test demonstrated the mixture catalyst has higher activity for DME partial oxidation and lower CH 4 selectivity than the individual Pt/Al 2 O 3 and Ni/MgO catalysts. O 2 -TPO analysis demonstrated that the mixture catalyst also had much higher coke resistance than sintered Ni-YSZ anode, especially at high O 2 to DME ratio. Raman spectroscopy of the carbon-deposited catalysts demonstrates that the graphitization degree of carbon is reduced with introducing O 2 into DME, and the carbon deposited on the mixture catalyst is almost in amorphous structure. Two operation modes of the mixture catalyst for indirect internal partial oxidation of DME, i.e, directly depositing on the anode surface and locating in the anode chamber were tried. The performance of the cells operating on DME fuel through both operation modes was studied by I – V polarization test and EIS characterization. The cells delivered attractive peak power density of around 750 mW cm −2 by operating on DME-O 2 mixture gas, modestly lower than 1012–1065 mW cm −2 operating on pure hydrogen fuel at 700 °C. The direct deposition of Pt/Al 2 O 3 –Ni/MgO onto anode surface to perform as a functional layer and a DME to O 2 ratio of 2:1 in the mixture gas is preferred to minimize coke formation and maximize power output for the cell to operate on DME fuel.

Sm0.5Sr0.5MO3−δ (M = Co and Mn) materials are synthesized, and their properties and performance as cathodes for solid oxide fuel cells (SOFCs) on Sm0.2Ce0.8O1.9 (SDC) and Y0.16Zr0.92O2.08 (YSZ) electrolytes are comparatively studied. The phase structure, thermal expansion behavior, oxygen mobility, oxygen vacancy concentration and electrical conductivity of the oxides are systematically investigated. Sm0.5Sr0.5CoO3−δ (SSC) has a much larger oxygen vacancy concentration, electrical conductivity and TEC than Sm0.5Sr0.5MnO3−δ (SSM). A powder reaction demonstrates that SSM is more chemically compatible with the YSZ electrolyte than SSC, while both are compatible with the SDC electrolyte. EIS results indicate that the performances of SSC and SSM electrodes depend on the electrolyte that they are deposited on. SSC is suitable for the SDC electrolyte, while SSM is preferred for the YSZ electrolyte. A peak power density as high as 690 mW cm−2 at 600 °C is observed for a thin-film SDC electrolyte with SSC cathode, while a similar cell with YSZ electrolyte performs poorly. However, SSM performs well on YSZ electrolyte at an operation temperature of higher than 700 °C, and a fuel cell with SSM cathode and a thin-film YSZ electrolyte delivers a peak power density of ∼590 mW cm−2 at 800 °C. The poor performances of SSM cathode on both YSZ and SDC electrolytes are obtained at a temperature of lower than 650 °C.

Single-chamber solid oxide fuel cells (SC-SOFCs), which apply fuel-oxidant (air) gas mixture as the atmosphere for both anode and cathode, are receiving many interests recently. This study aims to clarify the mechanism of oxygen reduction and methane oxidization over La0.8Sr0.2MnO3 (LSM) cathode in SC-SOFCs by an electrochemical method in combination with mass spectrometry (MS). Before cathodic polarization, a large polarization resistance (Rp) for oxygen reduction reaction (ORR) was observed and methane did not cause obvious effect on ORR because of the weak adsorption of methane over LSM surface. Cathodic polarization could decrease the Rp obviously due to the in-situ creation of oxygen vacancies; methane likely adsorbed on those oxygen vacancy sites to enhance its effect on ORR. Both the anodic and cathodic polarizations significantly increased the rate of methane oxidation over LSM electrode; in particular, the pumped oxygen anion was highly active for methane oxidation.

We have successfully fabricated a dense-type Scandia-stabilized zirconia (ScSZ) thin-film electrolyte with thickness down to ∼4 μm for intermediate temperature solid oxide fuel cells (IT-SOFCs; 600–800 °C) by a wet powder spraying technique. With an anode-supported design and a La0.8Sr0.2Sc0.1Mn0.9O3 (LSScM) oxide cathode, a peak power density of 788 mW cm−2 was achieved at 800 °C for a cell operating on hydrogen fuel. The impedance results demonstrated that the electrode polarization resistance is the main source of electrochemical performance loss for the single cell. Ba0.5Sr0.5Co0.8Fe0.2O3−δ + Sm0.2Ce0.8O1.9 (BSCF + SDC) composite cathode was then applied to improve the cell power output. An SDC interlayer was adopted to avoid the interfacial phase reaction between ScSZ and BSCF, which was also fabricated by the wet powder spraying. The effect of interlayer processing on the morphology and cell performance was studied by SEM-EDX, I–V polarization and EIS. Pre-sintering of the ScSZ layer was found to be superior to the co-sintering of SDC interlayer and ScSZ electrolyte layer. An anode-supported cell with SDC interlayer fabricated on pre-sintered ScSZ electrolyte film and a BSCF + SDC cathode delivered a peak power density as high as 1760 mW cm−2 at 800 °C.

Hydrous hydrazine is a hydrogen carrier in liquid state at room temperature, having high hydrogen content, and free of CO and other carbon-containing gases. In this study, the effects of oxides properties on the initial catalytic activity towards hydrous hydrazine decomposition as hydrogen source for proton exchange membrane fuel cells (PEMFCs) were systematically investigated. The results showed that the perovskite structure, cobalt ion and oxygen nonstoichiometry of oxides have important influence on the catalytic decomposition of hydrous hydrazine. The hydrogen selectivity of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), SrCoO3−δ (SC) and La0.2Sr0.8CoO3−δ (LSC2) catalysts with KOH promoter for hydrous hydrazine decomposition was compared at 55 °C, which indicated that hydrogen selectivity of BSCF and LSC2 could reach 100%. The performance of a PEMFC operating on the decomposition products from hydrous hydrazine was also studied and compared with that operating on pure hydrogen. The cell delivered a peak power density of 510 mW cm−2 at 50 °C by operating on the gaseous decomposition products of hydrous hydrazine, which was only slightly lower than that of a similar cell with pure hydrogen as fuel, due to the diluting effect of nitrogen. It highly promises hydrous hydrazine as a indirect fuel of PEMFCs for portable application.

This study characterizes BaCo0.7Fe0.2Nb0.1O3−δ (BCFN) perovskite oxide and evaluates it as a potential cathode material for proton-conducting SOFCs with a BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolyte. A four-probe DC conductivity measurement demonstrated that BCFN has a modest electrical conductivity of 2–15 S cm−1 in air with p-type semiconducting behavior. An electrical conductivity relaxation test showed that BCFN has higher Dchem and Kchem than the well-known Ba0.5Sr0.5Co0.8Fe0.2O3−δ oxide. In addition, it has relatively low thermal expansion coefficients (TECs) with values of 18.2 × 10−6 K−1 and 14.4 × 10−6 K−1 at temperature ranges of 30–900 °C and 30–500 °C, respectively. The phase reaction between BCFN and BZCY was investigated using powder and pellet reactions. EDX and XRD characterizations demonstrated that BCFN had lower reactivity with the BZCY electrolyte than strontium-containing perovskite oxides such as SrCo0.9Nb0.1O3-δ and Ba0.6Sr0.4Co0.9Nb0.1O3−δ. The impedance of BCFN was oxygen partial pressure dependent. Introducing water into the cathode atmosphere reduced the size of both the high-frequency and low-frequency arcs of the impedance spectra due to facilitated proton hopping. The cathode polarization resistance and overpotential at a current density of 100 mA cm−2 were 0.85 Ω cm−2 and 110 mV in dry air, which decreased to 0.43 Ω cm−2 and 52 mV, respectively, in wet air (∼3% H2O) at 650 °C. A decrease in impedance was also observed with polarization time; this was possibly caused by polarization-induced microstructure optimization. A promising peak power density of ∼585 mW cm−2 was demonstrated by an anode-supported cell with a BCFN cathode at 700 °C.

Ni-Al 2 O 3 composites with varying contents of nickel are synthesized via a glycine nitrate process (GNP) and an impregnation process (IMP). Their potential application as an anode functional layer for internal methane CO 2 reforming in a solid oxide fuel cell is investigated. H 2 -TPR results show that the chemical interaction between NiO and Al 2 O 3 decreases as the nickel content increases. Catalytic tests demonstrate that 15 wt.% Ni-Al 2 O 3 catalysts exhibit the best catalytic activity for methane CO 2 reforming. However, the carbon formation rates over Ni-Al 2 O 3 prepared via GNP are lower than those over Ni-Al 2 O 3 prepared via IMP using the same amounts of nickel, with the exception of the 1 wt.% Ni-Al 2 O 3 catalyst. Raman spectroscopy and O 2 -TPO results indicate that the degree of graphitization and the amount of carbon deposited on the 15 wt.% Ni-Al 2 O 3 catalyst synthesized via GNP are lower than those of the catalyst prepared via IMP following a 60 h stability test. A cell with a 15 wt.% Ni-Al 2 O 3 catalyst layer prepared via GNP is fabricated that delivers a peak power density of 1006 mW cm −2 at 850 °C when operating on methane-CO 2 gas mixtures, which is comparable to that observed when operating on hydrogen fuel.

The influence of Ba nonstoichiometry on the phase structure, sintering, electrical conductivity and chemical stability under CO 2 atmosphere of proton conductors with a nominal composition of Ba 1± x Ce 0.4 Zr 0.4 Y 0.2 O 3− δ (B 1± x ZCY4, 0 ≤ x ≤ 0.20) was systematically investigated. A complexing sol-gel process was applied to synthesize the B 1± x ZCY4 powders. The X-ray diffraction patterns of the well-calcined powders indicate that the specimens with 0 ≤ x ≤ 0.10 possessed a single-phase of orthorhombic perovskite-type oxides. Additionally, impurity phases of (Y,Ce)O 2− δ existed in B 1− x ZCY4, and BaCO 3 was found in B 1+ x ZCY4 with x = 0.15 and 0.20. After sintering at 1500 °C for 5 h, all B 1+ x ZCY4 samples became pure phased, whereas impurities still existed in samples with large Ba deficiencies. A study of the sintering behavior showed that the proper amount of Ba excess or deficiency facilitated electrolyte densification and that a large Ba nonstoichiometry hindered sintering. The electrical conductivities of B 1± x ZCY4 specimens with 0 ≤ x ≤ 0.05 were studied in the temperature range of 100–700 °C, and the results showed that the Ba nonstoichiometry influenced the electrical conductivity, especially with respect to grain boundary resistance. The chemical stability was also studied using temperature-programmed CO 2 desorption, and it was determined that the chemical stability was affected by the Ba content.

Different concentrations of copper are added to LiLaNi–Al 2 O 3 to improve the electronic conductivity property for application as the materials of the anode catalyst layer for solid oxide fuel cells operating on methane. Their catalytic activity for the methane partial oxidation, steam and CO 2 reforming reactions at 600–850 °C is systematically investigated. Among the three catalysts, the LiLaNi–Al 2 O 3 /Cu (50:50, by weight) catalyst presents the best catalytic activity. Thus, the catalytic stability, carbon deposition and surface conductivity of the LiLaNi–Al 2 O 3 /Cu catalyst are further studied in detail. O 2 -TPO results indicate that the coking resistance of LiLaNi–Al 2 O 3 /Cu is satisfactory and comparable to that of LiLaNi–Al 2 O 3 . The surface conductivity tests demonstrate it is extremely improved for LiLaNi–Al 2 O 3 catalyst due to the addition of 50 wt.% copper. A cell with LiLaNi–Al 2 O 3 /Cu (50:50) catalyst layer is operated on mixtures of methane–O 2 , methane–H 2 O and methane–CO 2 , and peak power densities of 1081, 1036 and 988 mW cm −2 are obtained at 850 °C, respectively, comparable to the cell with LiLaNi–Al 2 O 3 catalyst layer. In summary, the results of the present study indicate that LiLaNi–Al 2 O 3 /Cu (50:50) catalysts are highly coking resistant and conductive catalyst layers for solid oxide fuel cells.

We proposed a novel way to improve the cell performance of proton-conducting solid-oxide fuel cells by increasing the chemical interaction between the anode components using BaZr 0.4 Ce 0.4 Y 0.2 O 3−δ (BZCY4) as the ionic conducting phase of anode for a fuel cell with a BaCe 0.8 Y 0.2 O 3−δ (BCY) electrolyte. The strength of the chemical interaction between NiO and the ionic conducting phase (BZCY4 or BCY) was analyzed by the hydrogen temperature-programmed reduction (H 2 -TPR) technique. The effect of chemical interaction between NiO and the ionic conducting phase on the NiO diffusivity was investigated by SEM-EDX. The results demonstrated NiO had a much stronger interaction with BZCY4 than with BCY, thereby resulting in suppressed diffusivity of NiO into the BCY electrolyte. Using BZCY4 as the ionic conducting phase of the anode, a cell with an ohmic resistance of 0.65 Ω cm 2 at 700 °C was obtained. In contrast, a cell with BCY as the ionic conducting phase of the anode had an ohmic resistance of 0.82 Ω cm 2 at 700 °C. Therefore, the single cell with NiO + BZCY4 anode showed a peak power density higher than that of the cell with the NiO + BCY anode.

Ru–Al2O3 composites with varied Ru contents were synthesized by a glycine–nitrate combustion technique. Their potential application as anode catalyst functional layer of a solid–oxide fuel cell operating on methane fuel was investigated. Catalytic tests demonstrated the 3–7 wt.% Ru–Al2O3 composites had high catalytic activity for methane partial oxidation and CO2/H2O reforming reactions, while 1 wt.% Ru–Al2O3 had insufficient activity. The 3 wt.% Ru–Al2O3 catalyst also showed excellent operation stability and good thermal–mechanical compatibility with Ni–YSZ anode. H2-TPR and TEM results indicated there was strong interaction between RuOx and Al2O3 in the as-synthesized catalysts, which may account for the good catalytic stability of 3 wt.% Ru–Al2O3 catalyst. O2-TPO results demonstrated Ru–Al2O3 also had excellent coking resistance. Furthermore, the carbon deposited over Ru–Al2O3 had lower graphitization degree than that deposited over Ni–Al2O3, suggesting the easier elimination of potential carbon deposited over the Ru–Al2O3 catalysts. A cell with 3 wt.% Ru–Al2O3 catalyst functional layer was prepared, wh-ich delivered peak power densities of 1006, 952 and 929 mW cm−2 at 850 °C, operating on methane–O2, methane–H2O and methane–CO2 gas mixtures, respectively, comparable to that operating on hydrogen fuel. It highly promised 3 wt.% Ru–Al2O3 as a coking resistant catalyst layer for solid–oxide fuel cells.

A proton-conducting solid oxide fuel cells with a dual-layer electrolyte, constructed of a highly protonic conductive BaCe0.8Y0.2O3−δ (BCY) electrolyte and chemically stable BaZr0.4Ce0.4Y0.2O3−δ (BZCY4) electrolyte, was easily fabricated by dry pressing the electrolyte powders onto an NiO + BZCY4 anode substrate, followed by co-sintering at a high temperature. The performance of the as-fabricated cell with the BCY and BZCY4 dual-layer electrolyte was studied. Peak power densities of 249 and 101 mW cm−2 were achieved at 700 and 500 °C, respectively. Zinc was applied as a sintering promoter to increase the relative density of the BZCY4 electrolyte. Cross-sectional micrographs of the as-fabricated, dual-layer electrolyte cells were obtained by scanning electron microscopy. The results showed that the sintering ability of BZCY4 was improved by using zinc as sintering aid. A cell with BCY and zinc-modified BZCY4 dual-layer electrolyte delivered peak power densities of 276 and 247 mW cm−2 and OCVs of 1.03 and 1.02 V at 700 °C under humidified hydrogen and 15% CO2-containing hydrogen atmospheres, respectively. The operation stability of the dual-layer electrolyte cell under a 15% CO2-containing hydrogen atmosphere was also investigated.

In order to improve the single-chamber performance of a traditional anode-supported single-chamber solid-oxide fuel cell with NiO–ScSZ anode and ScSZ electrolyte, the modification of the anode with a fine nickel catalyst by impregnation method was exploited. Catalytic test demonstrated the nickel catalyst had higher catalytic activity than the severe sintered nickel–cermet anode between 700 and 900 °C, especially at the lower temperature range. SEM examination demonstrated the nickel catalyst impregnation increased the roughness of the nickel grains within the anode. Furthermore, some surfaces of the ScSZ grains are also covered with very fine nickel catalyst. By operating on a methane-air mixture gas with methane to oxygen ratio of 1.3:1, the cell with its anode impregnated with the nickel catalyst showed an open circuit voltage and peak power density of 0.954 V and 119 mW cm−2 at a furnace temperature of 750 °C, respectively, as a comparison of 0.893 V and 79 mW cm−2 for the cell without the nickel catalyst. The improved cell performance was attributed to the higher cell temperature and increased anode catalytic activity for methane partial oxidation.

This paper presents a systematic study of a direct-flame solid oxide fuel cell (DF-SOFC) operating on methanol and ethanol flames by SEM, EIS, I-V polarization and mass spectrometer (MS) characterizations and numerical simulation. The experimental study demonstrated that, by adopting a conventional Ni + Sm_(0.2)Ce_(0.8)O_(1.9) (SDC) anode, irreversible carbon deposition and a drop of cell performance was observed when running the cell on an ethanol flame, while no carbon was deposited by operating on a methanol flame. Fuel cell stability tests indicated significant degradation in performance after 3 h of operation on an ethanol flame, while no degradation was observed after 30 h of operation on a methanol flame. A simple qualitative explanation of the difference observed in the electrochemical performance for the fuel cell operating on a methanol flame and an ethanol flame is presented based on numerical simulation.

Hydrazine is a promising fuel for portable fuel cells because it is a liquid, it is carbon free and it has a high energy density. In this work, hydrazine was investigated as an efficient fuel for low temperature solid-oxide fuel cells (SOFCs) with a traditional nickel anode. A catalytic system with high selectivity toward hydrogen was developed using Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) as the main catalyst and potassium hydroxide as the promoter. The result of compositional analysis of the products showed that the hydrazine can be decomposed into hydrogen and nitrogen with 100% selectivity when an appropriate amount of KOH promoter is used. Acceptable power densities were achieved for a thin-film samaria-doped ceria (SDC) electrolyte cell operating on hydrazine decomposition products and hydrogen over a complete operation temperature range of 650–450 °C. In addition, a similar cell with ammonia as the fuel displayed a much lower performance.